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Motion blur bug
Closed, ArchivedPublic

Description

System Information
Operating system and graphics card
Win 7, (CPU render)

Blender Version
Broken: 2.77

Worked: (optional)

Short description of error
Some frames in my file seems to have bug with motion blur, or something similar. Animation is done with explosion modifier and the pieces are very close of each other.

Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps
Not exactly sure what causes the problem, so here is the file and my Blender artists thread.
http://blenderartists.org/forum/showthread.php?395124-Random-blurry-artifacts-in-cycles-rendering

Details

Type
Bug

Event Timeline

Artturi Mäntysaari (Armmm) created this task.
Artturi Mäntysaari (Armmm) raised the priority of this task from to Needs Triage by Developer.

I could not edit this bug report, so here is some additional info:

If I unselect motion blur, the problem does not happen anymore in those frames.
I started this project with 2.6a and then I downloaded 2.77 and noticed the same problem also there.
Frames with that problem takes lot more time to render than other frames.
If I apply solidify modifier, the problem does not happen anymore (but the quality of the animation is not what I was targeting)

Sergey Sharybin (sergey) closed this task as Archived.
Sergey Sharybin (sergey) claimed this task.

It usually saves time if the small file attached directly to the report, we don't have time to follow forums anyway.

The issue with your setup is that the object changes topology, which isn't supported by Cycles -- when using deformation motion blur the topology should match across all frames. This isn't a bug but rather a known limitation. Thanks for the report anyway.